1. Field of the Invention
The present invention relates to the production of polyphenylene sulfide fibers and products including the same.
2. Description of the Related Art
Filtration processes are used to separate compounds of one phase from a fluid stream of another phase by passing the fluid stream through filtration media, which traps the entrained or suspended matter. The fluid stream may be either a liquid stream containing a solid particulate or a gas stream containing a liquid or solid aerosol.
For example, filters are used in collecting dust emitted from incinerators, coal fired boilers, metal melting furnaces and the like. Such filters are referred to generally as “bag filters.” Because exhaust gas temperatures can be high, bag filters used to collect hot dust emitted from these and similar devices are required to be heat resistant. Bag filters can also be used in chemically corrosive environments. Thus, dust collection environments can also require a filter bag made of materials that exhibit chemical resistance. Examples of common filtration media include fabrics formed of aramid fibers, polyimide fibers, fluorine fibers and glass fibers.
Polyphenylene sulfide (PPS) polymers exhibit thermal and chemical resistance. As such, PPS polymers can be useful in various applications. For example, PPS can be useful in the manufacture of molded components for automobiles, electrical and electronic devices, industrial/mechanical products, consumer products, and the like.
PPS has also been proposed for use as fibers for filtration media, flame resistant articles, and high performance composites. Despite the advantages of the polymer, however, there are difficulties associated with the production of fibers from PPS.
It is difficult to spin PPS fibers from a spunbond process over a commercially useful period of time. Commercially available PPS resins have either too low or too high of a viscosity for a spunbond process. A low viscosity PPS resin creates excessive breaks in the fibers and defects in the spunbond web. A high viscosity PPS resin creates too much torque in the extruder making the resin unspinnable.
What is needed is a spunbond process that can make PPS fibers that can be continuously spun with minimal disruption of the spinning process.